lib/async_req/async_req.h

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Infrastructure for async requests
   4    Copyright (C) Volker Lendecke 2008
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #ifndef __ASYNC_REQ_H__
  21 #define __ASYNC_REQ_H__
  22
  23 #include "lib/talloc/talloc.h"
  24
  25 /**
  26  * An async request moves between the following 4 states:
  27  */
  28
  29 enum async_req_state {
  30         /**
  31          * we are creating the request
  32          */
  33         ASYNC_REQ_INIT,
  34         /**
  35          * we are waiting the request to complete
  36          */
  37         ASYNC_REQ_IN_PROGRESS,
  38         /**
  39          * the request is finished
  40          */
  41         ASYNC_REQ_DONE,
  42         /**
  43          * A user error has occured
  44          */
  45         ASYNC_REQ_USER_ERROR,
  46         /**
  47          * Request timed out
  48          */
  49         ASYNC_REQ_TIMED_OUT,
  50         /**
  51          * No memory in between
  52          */
  53         ASYNC_REQ_NO_MEMORY
  54 };
  55
  56 /**
  57  * @brief An async request
  58  *
  59  * This represents an async request being processed by callbacks via an event
  60  * context. A user can issue for example a write request to a socket, giving
  61  * an implementation function the fd, the buffer and the number of bytes to
  62  * transfer. The function issuing the request will immediately return without
  63  * blocking most likely without having sent anything. The API user then fills
  64  * in req->async.fn and req->async.priv, functions that are called when the
  65  * request is finished.
  66  *
  67  * It is up to the user of the async request to talloc_free it after it has
  68  * finished. This can happen while the completion function is called.
  69  */
  70
  71 struct async_req {
  72         /**
  73          * @brief The external state - will be queried by the caller
  74          *
  75          * While the async request is being processed, state will remain in
  76          * ASYNC_REQ_IN_PROGRESS. A request is finished if
  77          * req->state>=ASYNC_REQ_DONE.
  78          */
  79         enum async_req_state state;
  80
  81         /**
  82          * @brief Private pointer for the actual implementation
  83          *
  84          * The implementation doing the work for the async request needs a
  85          * current state like for example a fd event. The user of an async
  86          * request should not touch this.
  87          */
  88         void *private_data;
  89
  90         /**
  91          * @brief Print yourself, for debugging purposes
  92          *
  93          * Async requests are opaque data structures. The implementation of an
  94          * async request can define a custom function to print more debug
  95          * info.
  96          */
  97         char *(*print)(TALLOC_CTX *mem_ctx, struct async_req *);
  98
  99         /**
 100          * @brief status code when finished
 101          *
 102          * This status can be queried in the async completion function. It
 103          * will be set to 0 when everything went fine.
 104          **/
 105         uint64_t error;
 106
 107         /**
 108          * @brief What to do on completion
 109          *
 110          * This is used for the user of an async request, fn is called when
 111          * the request completes, either successfully or with an error.
 112          */
 113         struct {
 114                 /**
 115                  * @brief Completion function
 116                  * Completion function, to be filled by the API user
 117                  */
 118                 void (*fn)(struct async_req *);
 119                 /**
 120                  * @brief Private data for the completion function
 121                  */
 122                 void *priv;
 123         } async;
 124 };
 125
 126 struct async_req *async_req_new(TALLOC_CTX *mem_ctx);
 127
 128 char *async_req_print(TALLOC_CTX *mem_ctx, struct async_req *req);
 129
 130 void async_req_done(struct async_req *req);
 131
 132 void async_req_error(struct async_req *req, uint64_t error);
 133
 134 bool async_req_nomem(const void *p, struct async_req *req);
 135
 136 bool async_post_error(struct async_req *req, struct tevent_context *ev,
 137                       uint64_t error);
 138
 139 bool async_req_is_error(struct async_req *req, enum async_req_state *state,
 140                         uint64_t *error);
 141
 142 struct async_req_queue;
 143
 144 struct async_req_queue *async_req_queue_init(TALLOC_CTX *mem_ctx);
 145
 146 bool async_req_enqueue(struct async_req_queue *queue,
 147                        struct tevent_context *ev,
 148                        struct async_req *req,
 149                        void (*trigger)(struct async_req *req));
 150
 151 bool _async_req_setup(TALLOC_CTX *mem_ctx, struct async_req **preq,
 152                       void *pstate, size_t state_size, const char *_typename);
 153
 154 #define async_req_setup(_mem_ctx, _preq, _pstate, type) \
 155         _async_req_setup((_mem_ctx), (_preq), (_pstate), sizeof(type), #type)
 156
 157
 158 #endif